ZOOLOGY A.ND BOTANY, MICROSCOPY, ETC. 823 



of varying size may be fitted as required. The funnel is placed some 

 20 cm. above the specimen to be injected ;' this height gives sufficient 

 pressure. The funnel and cannula are kept warm by means of a ring- 

 burner and gas flame during the injection ; the alloy is then poured 

 into the funnel. When the specimen is sufficiently injected it isallowed 

 to cool, and after the lapse of \ hour it may be cut off from the cannula. 

 It is then placed in cold running water for 2 hours, and on removal all 

 superfluous parts are removed. In order to obtain the casts of the 

 lumina of the tubes or vessels, the organic material is digested away in 

 artificial gastric juice at 50°. After 24 hours the preparation is washed 

 in running water and then, if necessary, further cleaned with a brush. 



New Method for the Detection of Tubercle bacilli in Sputum.* 

 E. W. Eurich recommends the following procedure. A quantity of the 

 sputum is shaken up with "antiformin " in a glass-stoppered vessel, 

 such as a measure cylinder ("antiformin" = 15 p.c. liq. sod. hydrat. 

 -fliq. sodae. chlorinat. aa), the proportion of "antiformin" depending 

 upon the consistence of the sputum ; if the latter is very viscid or dense 

 an equal proportion may be required ; if thin, then half the amount 

 may suffice. The mixture is occasionally shaken during five minutes ; it 

 is then diluted with a volume of distilled water approximately ten times 

 as great as that of the " antiformin " used, and again shaken for a few 

 minutes. Finally, there is added a mixture of equal parts of ether 

 (methylated ether will do) and acetone equal in volume to that of the 

 water. It is shaken once more for a few seconds and the whole allowed 

 to stand. In a few minutes the contents of the bottle will be found to 

 separate into three layers. The middle layer, appearing as a more or less 

 dense white ring, will contain nearly all the tubercle bacilli that may be 

 present in the sputum, and can be drawn off with ease by means of a 

 pipette fitted with a teat. The density of this middle layer can be in- 

 creased after it has been pipetted off, if desired, with the help of a 

 centrifuge (an ordinary hand centrifuge will answer the purpose), but 

 it is not necessary. A film is made, dried, and fixed in the usual way, by 

 passing it through a flame. Before staining the film it is immersed for 

 a few seconds in 5 p.c. sulphuric acid to neutralize any adhering alkali, 

 and washed to remove the acid. If the examiner is interrupted, or other- 

 wise pressed for time, the whole mixture may be allowed to stand till 

 the next day or even longer ; the acid-fast property of the bacilli is 

 not affected by the delay. The sputum-antiformin mixture should be 

 diluted with distilled not with tap-water, as the latter may contain acid- 

 fast bacilli. 



Negative Staining of Bacteria,f — H. Fischer, after alluding to 

 Burri's indian-ink method, describes his experience with anihn dyes, 

 such as Con^o-red and nigrosin. A drop of the fluid containing bacteria 

 is mixed with a drop of similar bulk of a saturated solution of Congo-red 

 or nigrosin, and a film made in the usual way. When dry the film may 

 be mounted in balsam. The solution maybe heated previous to use. 



* Brit. Med. Journ. (1911) ii. p. 596. 



t Zeitschr. wiss. Mikrosk., xxvii. (1910) pp. 475-G. 



